Door Mimic

Medium monstrosity, shapechanger, neutral

Armor Class 12

Hit Points 58 9d8+18

Speed 15ft

STR

17 +3

DEX

12 +1

CON

15 +2

INT

5 -3

WIS

13 +1

CHA

8 -1

Skills Stealth +5

Damage Immunities Acid

Condition Immunities Prone

Senses Darkvision 60 ft., Passive Perception 11

Challenge 2

1/day: Mass Suggestion

Shapechanger. The mimic can use its action to polymorph into an object or back into its true, amorphous form. Its statistics are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies. Adhesive (Object Form Only). The mimic adheres to anything that touches it. A Huge or smaller creature adhered to the mimic is also grappled by it (escape DC 13). Ability checks made to escape this grapple have disadvantage. False Appearance (Object Form Only). While the mimic remains motionless, it is indistinguishable from an ordinary object. Grappler. The mimic has advantage on attack rolls against any creature grappled by it.

Actions

Pseudopod. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 7 1d8+3 bludgeoning damage. If the mimic is in object form, the target is subjected to its Adhesive trait. Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 7 1d8+3 piercing damage plus 4 1d8 acid damage.

A door that is a mimic

Any doorway that could feasibly contain a door mimic